Process for the manufacture of phthalic anhydrid, phthalic acid, benzoic acid, and naphthaquinones.



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HARRY D. GIBBS, OF SAN FRANCISCO, CALIFORNIA, AND COURTNEY CONOVER. OF PHILADELPHIA, PENNSYLVANIA.

PROCESS FOR THE MANUFACTURE OF PI'ITHALIC ANHYDRID, PI'I'IHALIC ACID, BENZOIC ACID, AND NAPHTHAQUINONES.

No Drawing.

Specification of Letters Patent.

(DEDICATED TO THE PUBLIC.)

To all whom it may concern:

Be it known .that we, HARRY D. GIBBS and COURTNEY CoNovER, citizens of the United States of America, residing in the city of San F rancisco, county of San Francisco, State of California, and in the city of Philadelphia, county of Philadelphia, State of Pennsylvania,respectively, (whose post-oflice address is WVashingtomD. C.,) have invented a new and useful Process for the Manufacture of Phthalic Anhydrid, Phthalic Acid, Benzoic Acid, and Naphthaquinones.

This application is made under the act of March 3, 1883, chapter 143- (22 Stat., 625), and the invention herein described and claimed may be used by the Government of the United States or any of its ollicers or employees in the prosecution of Work for the Government, or any person in theUnited S1tates, without payment to us of any roya ty.

Our invention relates to a process for the manufacture of phthalic anhydrid, phthalic acid, benzoic acid and naphthaquinones from produced in forms which make them cliflicult to separate and purify. The object ofv our invention is to provide a-process for the manufacture of the materials named which will be free'from the objectionable features of the processes employed'at present.

Our invention consists in the production of phthalic anhydrid, phthalic acid, benzoic acid and naphthaquinones from naphthalene by heating the naphthalene until it passes into the vapor phase, mixing this naphthalene vapor with an oxygen-containing gas mixture, forclng this mixture of gases into .to cause them Phthalic anhydrld, together with small por- ,tions of other oxldat-ion products, is sepaclose contact with finely divided oxids of molybdenum, heated to a temperature ranging from 250 C. to 650 C., under which treatment the naphthalene is oxidized to form the valuable products named, together with carbon dioxid and Water.

To illustrate the practical operation of our process we shall describe in detail the: preferred procedure. Naphthalene is melted and is caused toflow continuously at a measured rate into a heated chamber where it is volatilized. This vapor of naphthalene is then mixed with air in excess of the proportion theoretically required to oxidize naphthalene to phthalic anhydridf The mixture of air and naphthalene vapor is passed into a reaction chamber maintained at a temperature ranging from 350 to 550f 0., the preferred temperature being 500 C. This procedure produces the largest yields of phthalic anhydrid. In this chamber the gas mixture is forced into close contact with oxide of molybdenum der. This powder is supported on trays where, by means of battle plates, the current ofmixed gases is forced through it. The gases are kept under pressure only sufficient to flow continuously through the reaction chamber. The products of the reaction, consisting of phthalic anhydrid and other oxidation products of naphthalene, are condensed, together with unchanged naphthalene, by well-known processes.

rated from the unchanged naphthalene by fractional sublimation.

We have discovered that the process as above described may be varied in many ways and yet will produce one or all of the oxidation products named. Thus, oxygen may be substituted Wholly or in part for air, or air may be mixed with a gas which is relatively inert under the conditions obtaining in the process. The oxide of molybdenum may be mixed with or combined with other substances, such as other metallic oxids, asbestos, pumice stone, or other inert materials. The gas mixture may be brought in contact With or forced through the catalyst in many difi'erent Ways. The proportion of naphthalene vapor to the oxygen-containing gas mix- Patented Nov. 12, 1918.

Application filed May 12, 1917. Serial No. 168,216.

ture maybe varied Within wide limits. And phthalic 'anhydrid, phthalic acid, benzoic the reaction products may be separated by acid and naphthaquinones, which process 25' various Well-known means. differing from consists in. subjecting naphthalene in the the fractional sublimation mentioned above. gaseous state and mixed With atmospheric 5 Thus the acid constituents may be'dissolved' air to the action of molybdenum oxids heated in alkaline solutionsand subsequently freed .to temperatures ranging from 350 to 550 from their salts by the addition of sulfuric centigrade. or phosphoric acid and then sublimed. Or '3. A process for the manufacture of the reaction products may be treated with phthalic anhydrid, phthalic acid, benz'oic l ammonia gas or aqueous solutions of am acid and naphthaquinones, Which process monia or various ar'nins to produce other useconsists in subjecting naphthalene in the ful and valuable compounds. gaseous state and mlxed with an oxygen- 35 Having thus described our invention we containing gas mixture, to the action of claim molybdenum oxids heated to temperatures 15 1. A process for the manufacture of ranging from 250 to 650 centigrade.

phthalic 'anhydrid, phthalic acid, benzoic In testimony whereof We aflix our sigma-- acid and naphthaqulnones, which process tures in the presence of two-subscribing Wit- 40 consists in subjecting naphthalene in the nesses. gaseous state and mixed with an oxy 'en-con- HARRY D. GIBBS. 20 taining gas-mixture, to the action ofmolyb- COURTNEY CONOV-ER; denum oxids heated to temperatures ranging Witnesses: 1 p i from 350 to 550centigrader GEORGE ALGEIGER, 2. A process" for the manufacture of j vIIERBEBT"11in.LUB'S. 

